dart2js cps: Fix bug in assignment propagation.

dart2js cps: Fix bug in assignment propagation.

BUG=
R=floitsch@google.com

Committed: https://github.com/dart-lang/sdk/commit/4660cd6833390bfad44bad00010840fa70b1caef

[asgerf, 2015-07-02 14:55:00]

asgerf@google.com changed reviewers:
+ floitsch@google.com

[asgerf, 2015-07-02 14:55:01]

https://codereview.chromium.org/1222673002/diff/1/pkg/compiler/lib/src/tree_i...
File pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart (right):

https://codereview.chromium.org/1222673002/diff/1/pkg/compiler/lib/src/tree_i...
pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart:382:
constantEnvironment.remove(assign.variable);
This matters for variables that have a single use but that use could not be
inlined into the successor statement because of a try block.

When the use is visited later, this code has already given up and left the
constant assignment here.

When we get to the use, it is important that it does not try to process the
constant again.

[floitsch, 2015-07-02 16:01:24]

LGTM.

https://codereview.chromium.org/1222673002/diff/1/pkg/compiler/lib/src/tree_i...
File pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart (right):

https://codereview.chromium.org/1222673002/diff/1/pkg/compiler/lib/src/tree_i...
pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart:382:
constantEnvironment.remove(assign.variable);
On 2015/07/02 14:55:01, asgerf wrote:
> This matters for variables that have a single use but that use could not be
> inlined into the successor statement because of a try block.
> 
> When the use is visited later, this code has already given up and left the
> constant assignment here.
> 
> When we get to the use, it is important that it does not try to process the
> constant again.

Can you put this as a comment?

[asgerf, 2015-07-02 16:09:45]

https://codereview.chromium.org/1222673002/diff/1/pkg/compiler/lib/src/tree_i...
File pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart (right):

https://codereview.chromium.org/1222673002/diff/1/pkg/compiler/lib/src/tree_i...
pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart:382:
constantEnvironment.remove(assign.variable);
On 2015/07/02 16:01:24, floitsch wrote:
> On 2015/07/02 14:55:01, asgerf wrote:
> > This matters for variables that have a single use but that use could not be
> > inlined into the successor statement because of a try block.
> > 
> > When the use is visited later, this code has already given up and left the
> > constant assignment here.
> > 
> > When we get to the use, it is important that it does not try to process the
> > constant again.
> 
> Can you put this as a comment?

Done.

[asgerf, 2015-07-02 16:13:45]

Committed patchset #3 (id:40001) manually as
4660cd6833390bfad44bad00010840fa70b1caef (presubmit successful).